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Keskitalo, Niklas
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Publications (10 of 13) Show all publications
Andersen, O., Björsell, N. & Keskitalo, N. (2009). A Test-Bed Designed to Utilize Zhu’s General Sampling Theorem to Characterize Power Amplifiers. In: Instrumentation and measurement technology conference 2009 I2MTC '09 IEEE. Paper presented at Instrumentation and measurement technology conference 2009 I2MTC '09 IEEE (pp. 201-204). Singapore
Open this publication in new window or tab >>A Test-Bed Designed to Utilize Zhu’s General Sampling Theorem to Characterize Power Amplifiers
2009 (English)In: Instrumentation and measurement technology conference 2009 I2MTC '09 IEEE, Singapore, 2009, p. 201-204Conference paper, Published paper (Refereed)
Abstract [en]

Characterizing power amplifiers require test set-ups with performance superior to the power amplifiers. A commonly used method is to use an IQ-demodulator. However, problem arises due to imperfections in the demodulator such as IQ-imbalance; an alternative method is to use a direct down converter to intermediate frequency. The drawback then is the limited bandwidth. However, the required bandwidth of the ADC does not need to be exceptional. According to Zhu’s general sampling theorem is it enough to sample the output signal at the Nyquist rate of the input. However, even though the required sampling rate is reduced the demands on the analog bandwidth remains. Unfortunately, commercially available instruments such as vector signal analyzers can not be used for this purpose since their analog bandwidth is too small. In this paper a test-bed is designed to utilize the Zhu’s general sampling theorem. The RF front-end has frequency range of 500 MHz – 2.7 GHz and a bandwidth of 1 GHz. All performance data are verified with measurements.

Place, publisher, year, edition, pages
Singapore: , 2009
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:hig:diva-4429 (URN)10.1109/IMTC.2009.5168443 (DOI)978-1-4244-3353-7 (ISBN)
Conference
Instrumentation and measurement technology conference 2009 I2MTC '09 IEEE
Note
Instrumentation and measurement technology conference 2009 I2MTC '09 IEEE 5-7 may 2009 SingaporeAvailable from: 2009-05-08 Created: 2009-05-08 Last updated: 2018-03-13Bibliographically approved
Nader, C., Altahir, H., Andersen, O., Björsell, N., Condo, E., Keskitalo, N. & De La Rosa, H. (2009). Automated multidimensional characterization of power amplifier for design and production. In: 2009 IEEE Instrumentation and Measurement Technology Conference Proceedings: . Paper presented at 26th IEEE International Instrumentation and Measurement Technology Conference, Singapore, 5-7 May 2009 (pp. 144-148). Singapore: I&M Society
Open this publication in new window or tab >>Automated multidimensional characterization of power amplifier for design and production
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2009 (English)In: 2009 IEEE Instrumentation and Measurement Technology Conference Proceedings, Singapore: I&M Society , 2009, p. 144-148Conference paper, Published paper (Refereed)
Abstract [en]

Designing, optimizing and producing modern power amplifiers (PA) requires new and fast RF (radio frequency) measurement techniques capable of characterizing its real behavior. Power amplifiers are a truly multidimensional device where many desired performance parameters are contradictory to each other. This is especially true for the generation of modern communication PAs that require high efficiency, high linearity as well as high bandwidth. This paper presents a software-defined measurement setup for fast and cost efficient multidimensional measurements based on highly accurate standard instruments and a PC. The test bed as well as the graphical user interface is presented along with a demonstration of its functionality. During tuning of tank networks, drain quiescent current, and bias conditions, 3-dimensional graphs can be selected for the most appropriate axes of trade-off parameters to display a true behavior of the PA under test subjected to real-world or close to real-world signals. The measurement system offers the possibility to monitor envelope-tracking dynamic power consumption up to 100 MHz plus the possibility to use high crest factors.

Place, publisher, year, edition, pages
Singapore: I&M Society, 2009
Keywords
Automated multidimensional measurements, power amplifier, time domain measurement, state-of-the-art test-bed, gain-distortion-efficiency
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:hig:diva-5486 (URN)10.1109/IMTC.2009.5168432 (DOI)000277153600027 ()978-1-4244-3352-0 (ISBN)
Conference
26th IEEE International Instrumentation and Measurement Technology Conference, Singapore, 5-7 May 2009
Projects
KKS DSM
Available from: 2009-09-26 Created: 2009-09-22 Last updated: 2018-03-13Bibliographically approved
Wisell, D., Stenvard, P., Hansebacke, A. & Keskitalo, N. (2009). Considerations when Designing Virtual Instruments. Gävle: Högskolan i Gävle
Open this publication in new window or tab >>Considerations when Designing Virtual Instruments
2009 (English)Report (Other academic)
Abstract [en]

In this paper the software and hardware structure of a virtual instrument measurement system is discussed. The focus is on flexibility, modularity, generality and hardware independence. A software architecture that meets these requirements is proposed and discussed in some detail. The proposed software architecture has a layered structure that makes it suitable for implementation of versatile measurement systems. The measurement functionality is encapsulated in its own, hardware independent layer and communicates with its environment, e.g. physical hardware, through intermediary software components. Finally a measurement system for characterization of power amplifiers that is designed following the proposed software architecture, with software driven measurements, is implemented.

Place, publisher, year, edition, pages
Gävle: Högskolan i Gävle, 2009. p. 6
Series
Working paper, ISSN 1403-8757 ; 41
Keywords
software driven measurements, software
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:hig:diva-4110 (URN)
Available from: 2009-04-16 Created: 2009-04-16 Last updated: 2018-03-13Bibliographically approved
Andersen, O., Wisell, D., Staenvard, P. & Keskitalo, N. (2009). Extending the Bandwidth and Dynamic Range of Old RF Instruments to Meet State-of-the-Art Performance, Using a Synthetic Instrument Approach. IEEE Transactions on Instrumentation and Measurement, 58(2), 248-254
Open this publication in new window or tab >>Extending the Bandwidth and Dynamic Range of Old RF Instruments to Meet State-of-the-Art Performance, Using a Synthetic Instrument Approach
2009 (English)In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 58, no 2, p. 248-254Article in journal (Refereed) Published
Abstract [en]

A decrease in life cycle cost is a key issue for testing mobile communication systems. The rapid development and edge technology requires high-performance instruments and state-of-the-art measurement technology. New investments are expensive, but even older generation instruments are capable of extending their bandwidth and dynamic range to meet even the latest Third-Generation Partnership Project (3GPP) cellular measurement requirements by the addition of external hardware using a synthetic instrument approach. The novelty of this paper is the high performance on the most crucial parameters, i.e., the dynamic range and bandwidth achieved by only replacing some parts of the legacy instrument. Moreover, the demonstrated direct IF synthesis has a high degree of novelty at wide modulation bandwidths. It is desired to use virtual/synthetic instruments and make the signal processing in the software independent of the hardware, i.e., software-defined measurements (SDMs). In this paper, a state-of-the-art experimental setup for signal generation and signal analysis is demonstrated. A direct IF synthesis is used to generate a wideband code-division multiple-access (WCDMA) carrier with more than 72-dB adjacent carrier leakage ratio (ACLR) up to 12 parallel carriers with more than 68-dBc ACLR over a total bandwidth of 100 MHz. The signal analysis capabilities (e.g., ACLR performance) for a WCDMA carrier is better than -70 dBc and for a continuous wave better than -85 dBc over a bandwidth of 42.5 MHz. The critical RF downconverter in the setup is carefully designed not to degrade the dynamic range performance.

Keywords
Bandwidth extension; Dynamic range; Measurement system; Signal analysis; Signal generation; Synthetic instruments
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:hig:diva-3880 (URN)10.1109/TIM.2008.2005972 (DOI)000262428800003 ()2-s2.0-60149100927 (Scopus ID)
Available from: 2009-03-06 Created: 2009-03-06 Last updated: 2018-03-13Bibliographically approved
Landin, P., Isaksson, M., Keskitalo, N. & Tornblad, O. (2009). Sideband asymmetries in RF Power LDMOS Before and After Digital Predistortion. Paper presented at Radio Frequency Measurement Technology Conference.
Open this publication in new window or tab >>Sideband asymmetries in RF Power LDMOS Before and After Digital Predistortion
2009 (English)Conference paper, Published paper (Other academic)
Abstract [en]

 The merging of the fields of RF engineering and signal processing has introduced concepts such as behavioral modeling and enabled digital linearization schemes for wireless devices, such as power amplifiers (PAs). Despite that this process has been going on for a number of years much work remains to be done. The links between physical behavior and mathematical models are far from well-understood as are the optimum strategies for device design. This study focus on digital predistortion properties of a one-stage PA consisting of a power transistor mounted in a test fixture. The device under test (DUT) is an Infineon PTF210451E, a 45W transistor intended for usage in the frequency bands 2010-2025 MHz and 2110-2170 MHz. The test fixture is also designed by Infineon Technologies.  The signal types used in the measurements are single and double carrier wideband code division multiple access (WCDMA) signals. The double carrier WCDMA signals have tone-spacings of 5, 10 and 15 MHz. Normal two-tone measurements are also presented. 

National Category
Telecommunications Signal Processing
Identifiers
urn:nbn:se:hig:diva-11176 (URN)
Conference
Radio Frequency Measurement Technology Conference
Available from: 2012-01-03 Created: 2012-01-02 Last updated: 2018-03-13Bibliographically approved
Landin, P. N., Nader, C., Björsell, N., Isaksson, M., Wisell, D., Händel, P., . . . Keskitalo, N. (2009). Wideband Characterization of Power Amplifiers Using Undersampling. In: 2009 IEEE MTT-S International Microwave Symposium: . Paper presented at IEEE/MTT-S International Microwave Symposium, Boston, MA, 7-12 June 2009 (pp. 1365-1368). Boston: IEEE MTT
Open this publication in new window or tab >>Wideband Characterization of Power Amplifiers Using Undersampling
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2009 (English)In: 2009 IEEE MTT-S International Microwave Symposium, Boston: IEEE MTT , 2009, p. 1365-1368Conference paper, Published paper (Refereed)
Abstract [en]

In this paper a radio frequency power amplifier is measured and characterized by the use of undersampling based on the generalized Zhu-Frank sampling theorem. A test system has been designed allowing the bandwidth of the stimuli signal to be 100 MHz in the characterization process. That would not be possible with any vector signal analyzer on the market. One of the more challenging problem within the proposed concept is the model validation process. Here, two different techniques for model validation are proposed, the multitone and the spectrum scan validation methods.

Place, publisher, year, edition, pages
Boston: IEEE MTT, 2009
Series
IEEE MTT-S International Microwave Symposium, ISSN 0149-645X
Keywords
Communication system performance, modeling, nonlinear systems, power amplifiers, radio transmitters.
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:hig:diva-5487 (URN)000273507400343 ()978-1-4244-2803-8 (ISBN)
Conference
IEEE/MTT-S International Microwave Symposium, Boston, MA, 7-12 June 2009
Projects
KKS SDM
Available from: 2009-09-26 Created: 2009-09-22 Last updated: 2018-11-26Bibliographically approved
Nader, C., Landin, P. N., Björsell, N., Isaksson, M., Wisell, D., Händel, P., . . . Keskitalo, N. (2009). Wideband Power Amplifiers Characterization by Undersampling: Zhu-Frank Sampling Theorem. Paper presented at RF measurement technology conference, Gävle, 2009.
Open this publication in new window or tab >>Wideband Power Amplifiers Characterization by Undersampling: Zhu-Frank Sampling Theorem
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2009 (English)Conference paper, Published paper (Other academic)
National Category
Telecommunications
Identifiers
urn:nbn:se:hig:diva-10563 (URN)
Conference
RF measurement technology conference, Gävle, 2009
Available from: 2011-09-29 Created: 2011-09-29 Last updated: 2018-11-26Bibliographically approved
Zenteno, E., Isaksson, M., Wisell, D., Keskitalo, N. & Andersen, O. (2008). An Envelope Domain Measurement Test Setup to Acquire Linear Scattering Parameters. In: 72nd ARFTG Conf. Dig., Portland, OR (pp. 54-57).
Open this publication in new window or tab >>An Envelope Domain Measurement Test Setup to Acquire Linear Scattering Parameters
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2008 (English)In: 72nd ARFTG Conf. Dig., Portland, OR, 2008, p. 54-57Conference paper, Published paper (Refereed)
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:hig:diva-3272 (URN)10.1109/ARFTG.2008.4804287 (DOI)978-1-4244-2300-2 (ISBN)
Available from: 2008-12-16 Created: 2008-12-16 Last updated: 2018-03-13Bibliographically approved
Andersen, O., Wisell, D. & Keskitalo, N. (2008). Measurement of ACLR with high dynamic range. In: IEEE MTT-S International Microwave Symposium Digest (pp. 273-277). Atlanta, GA
Open this publication in new window or tab >>Measurement of ACLR with high dynamic range
2008 (English)In: IEEE MTT-S International Microwave Symposium Digest, Atlanta, GA, 2008, p. 273-277Conference paper, Published paper (Other academic)
Abstract [en]

In this paper a method to overcome the insufficient dynamic range of RF measurement instruments, i.e. signal generators and spectrum analyzers, for distortion measurements on feedforward and other highly linear amplifiers, is discussed. A circuit board is designed, built and verified. Its performance is found to be superior to traditional methods using filters, both from a technical performance and flexibility standpoint as well as from an economic view. ACLR measurements for WCDMA signals can be done well below -70 dBc using the produced circuit board. © 2008 IEEE.

Place, publisher, year, edition, pages
Atlanta, GA: , 2008
Keywords
Intermodulation, Power amplifiers, Signal generators, Spectrum analyzers, Circuit boards, Distortion measurements, Dynamic ranges, Economic views, Feedforward, High Dynamic ranges, Linear amplifiers, RF measurements, Technical performances, WCDMA signals, Microwaves
Identifiers
urn:nbn:se:hig:diva-10392 (URN)10.1109/MWSYM.2008.4633156 (DOI)2-s2.0-57349167330 (Scopus ID)
Available from: 2011-09-25 Created: 2011-09-25 Last updated: 2018-03-13Bibliographically approved
Zenteno, E., Andersen, O., Isaksson, M., Keskitalo, N. & Wisell, D. (2008). Nonlinear Network Analysis for Modern Communication Devices and Systems. In: 72nd ARFTG Conf. Dig., Portland, OR (pp. 64-68).
Open this publication in new window or tab >>Nonlinear Network Analysis for Modern Communication Devices and Systems
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2008 (English)In: 72nd ARFTG Conf. Dig., Portland, OR, 2008, p. 64-68Conference paper, Published paper (Refereed)
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:hig:diva-3273 (URN)10.1109/ARFTG.2008.4804292 (DOI)978-1-4244-2300-2 (ISBN)
Available from: 2008-12-16 Created: 2008-12-16 Last updated: 2018-03-13Bibliographically approved
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